The present invention relates to a method of making foam material, and more particularly to a method of making useful foam material from waste foam material.
A U.S. patent bearing U.S. Pat. No. 3,452,122 discloses a method of making foam material by bonding together the particles of comminuted previously formed foam material and a foamable polyurethane resin composition. The foam material made by means of such method as mentioned above is provided with superior qualities of high density and high air permeability by virtue of the facts that the cavities of particles of comminuted foam material are filled with the new foam material and that the new foam material penetrates into the particles of comminuted foam material. However, the foam material made by the disclosed method mentioned above is defective in that it is not provided with a quality of strong tensile strength. According to the applicant of this patent application, the foamable polyurethane resin composition was found to be incapable of penetrating completely into the particles of comminuted foam material. Therefore, an improved method intended to provide a solution to the problem described above was disclosed by this applicant in a U.S. patent bearing U.S. Pat. No. 4,666,646. The method is characterized in that the particles of comminuted previously formed foam material are dried before they are mixed with the foamable polyurethane resin composition. As a result, the foam material so produced is found to have a greater tensile strength as compared with the foam material made by the other disclosed method mentioned above. This is due to the fact that the dried particles permit a relatively greater quantity of foamable polyurethane resin composition to penetrate thereinto. This improved method is by no means satisfactory. In addition, such improved method is a time-consuming process.